WO2020147185A1

WO2020147185A1 - Method for preparing graphene composite material, and polymer coating

Info

Publication number: WO2020147185A1
Application number: PCT/CN2019/078142
Authority: WO
Inventors: 王立平; 杜鹏; 王娟; 赵海超
Original assignee: 中国科学院宁波材料技术与工程研究所
Priority date: 2019-01-20
Filing date: 2019-03-14
Publication date: 2020-07-23
Also published as: CN109836871A

Abstract

Disclosed are a method for preparing a graphene composite material, and a polymer coating. The method comprises first fixing PEDOT:PSS between LDH layers by means of an intercalation method to obtain an intermediate product of PEDOT:PSS-LDH, and then assembling the intermediate product PEDOT:PSS-LDH to graphene so as to encapsulate the graphene. The graphene composite material has a high resistance with respect to charge transfer during electrocorrosion, can inhibit galvanic corrosion, has good isolation and anticorrosion effects, and can be used as a filler for a polymer coating to obtain a coating having both corrosion resistance and self-repairing abilities, thereby possessing a good protective effect on a matrix.

Description

A preparation method of graphene composite material and a polymer coating

Technical field

The invention relates to the technical field of graphene materials, in particular to a preparation method of graphene composite materials and a polymer coating.

Background technique

Graphene has impermeability, chemical stability and mechanical strength, and can be used as a filler for protective coatings on the surface of the substrate to improve its protective effect on the substrate. However, graphene also has high electrical conductivity, so it is easy to accelerate micro-galvanic corrosion when used as a coating filler.

Summary of the invention

The invention provides a method for preparing a graphene composite material, and the graphene composite material prepared by the method can inhibit electric corrosion.

The technical solution provided by the present invention is: a method for preparing a graphene composite material, including the following steps:

(1) Mix the raw materials for the synthesis of hydrotalcite with poly 3,4-ethylenedioxythiophene/polystyrene sulfonate (PEDOT:PSS), and prepare the intermediate product PEDOT:PSS-LDH by hydrothermal synthesis, wherein PEDOT: PSS intercalation to LDH;

(2) The intermediate product PEDOT:PSS-LDH and graphene oxide are electrostatically self-assembled and the graphene oxide is reduced to obtain the graphene composite material PEDOT:PSS-LDH/rGO.

Preferably, the raw materials of the synthetic hydrotalcite include aluminum salt, magnesium salt and urea, and the raw materials are synthesized by a blending precipitation method or a hydrothermal synthesis method.

Aluminum salts include, but are not limited to, one or more of nitrate, sulfate, chloride and the like.

Magnesium salts include, but are not limited to, one or more of nitrate, sulfate, chloride, and the like.

Preferably, in the step (1), the reaction temperature is 50-80°C, most preferably 60°C.

Preferably, in the step (1), the mass ratio of PEDOT:PSS to LDH is (0.69-1.15):1, most preferably 1:1.

Preferably, in the step (1), the molar ratio of aluminum salt, magnesium salt and urea is 1.6:1:(0.8-1.2), most preferably 1.6:1:1.

As an implementation manner, the step (1) is as follows:

Magnesium nitrate, aluminum nitrate, urea and PEDOT:PSS are mixed and put into a reaction tank for hydrothermal synthesis reaction. The reaction product is fully washed with ethanol and/or deionized water and dried to obtain the intermediate product PEDOT:PSS-LDH.

In the step (2), the method for reducing the graphene oxide is not limited, and includes reducing the graphene oxide to graphene in a reducing solution or a reducing atmosphere.

Preferably, in the step (2), the reduction reaction temperature is 50-100°C, most preferably 80°C.

Preferably, in the step (2), the mass ratio of graphene oxide to the intermediate product PEDOT:PSS-LDH is (3.0-5.0):1, most preferably 4.0:1.

As an implementation manner, the step (2) is as follows:

The intermediate product PEDOT:PSS-LDH is mixed with graphene oxide, the intermediate product PEDOT:PSS-LDH is electrostatically self-assembled on the surface of graphene oxide, and then the graphene oxide is reduced in a reducing atmosphere or a reducing solution to obtain the graphene composite material PEDOT: PSS-LDH/rGO.

Preferably, ultrasonic vibration is used after mixing.

Compared with the prior art, the present invention has the following advantages:

(1) The present invention uses PEDOT:PSS. PEDOT:PSS is a polythiophene conductive polymer with high electrical conductivity and environmental stability. The present invention first fixes PEDOT:PSS between LDH layers by intercalation method to obtain the intermediate product PEDOT:PSS-LDH, which not only ensures the integrity of the LDH layer structure, does not occur galvanic corrosion, and has certain characteristics of corrosion resistance At the same time, it gives the material PEDOT:PSS new characteristics; then the intermediate product PEDOT:PSS-LDH is assembled on graphene by electrostatic adsorption, that is, the graphene is modified with PEDOT:PSS intercalated LDH nanosheets, and the graphene is processed "Encapsulation" has a large resistance to charge transfer during the electro-corrosion process, thereby achieving the technical purpose of inhibiting galvanic corrosion and having a good isolation and corrosion protection.

(2) The method of the present invention has a simple preparation process and easy-to-obtain raw materials. The prepared graphene composite material can be used as a filler for polymer coatings, which not only maintains the original properties of graphene such as impermeability, chemical stability and high mechanical strength. , And extend the function of the diffusion path of the corrosive medium, and when the coating is stimulated by the environment, the divalent Mg ²⁺ ions from the LDH will promote the ionic cross-linking of the polymer, giving the coating a self-repairing function in response to environmental stimuli. It is also a kind of anti-corrosion, can avoid the phenomenon of accelerated corrosion of traditional polymer coatings with graphene as filler, and has self-repairing ability, so that it has a good protective effect on the substrate and is used in the ocean Corrosion-resistant coatings in other environments have good application prospects.

Said polymers include but are not limited to polyvinyl butyral (PVB). PVB resin has good corrosion resistance, bonding properties, mechanical properties and electrical insulation properties, and is widely used in construction, transportation, electronics, machinery and other fields.

In the polymer coating, the mass ratio of polymer to filler is 1:10-30, preferably 1:20, and the filler is the graphene composite material PEDOT:PSS-LDH/rGO prepared by the present invention .

As an implementation manner, the preparation method of the polymer coating is: coating, dipping or depositing the polymer coating solution on the surface of the substrate, and curing after drying. Wherein, the polymer coating solution includes polymer and the graphene composite material PEDOT:PSS-LDH/rGO prepared by the present invention.

BRIEF DESCRIPTION

FIG. 1 is the morphology of the poly 3,4-ethylenedioxythiophene/polystyrene sulfonate-hydrotalcite/graphene material prepared in Example 1.

Fig. 2 is a partial enlarged view of Fig. 1.

3 is a graph showing the electrochemical impedance performance of the poly 3,4-ethylenedioxythiophene/polystyrene sulfonate-hydrotalcite/graphene coating prepared in Example 1.

4 is a graph showing the electrochemical impedance performance of the poly 3,4-ethylenedioxythiophene/polystyrene sulfonate-hydrotalcite/graphene coating prepared in Example 1.

Fig. 5 is the FT-IR of the corrosion product of the poly 3,4-ethylenedioxythiophene/polystyrene sulfonate-hydrotalcite/graphene coating prepared in Example 1 on the steel surface, and after immersion And morphology.

detailed description

The present invention will be further described in detail below in conjunction with the embodiments and the drawings. It should be pointed out that the embodiments described below are intended to facilitate the understanding of the present invention, and do not have any limiting effect on it.

Example 1:

(1) Weigh 0.595 g of magnesium nitrate, and dissolve 0.96 g of aluminum nitrate into 200 ml of deionized water, mix well and add 0.6 g of urea to obtain a raw material solution.

(2) Add 0.06 g of PEDOT:PSS to the raw material solution of step (1), shake and heat in a hydrothermal reaction kettle for 24 hours to obtain the intermediate product PEDOT:PSS-LDH.

(3) Add graphene oxide to the intermediate product prepared in step (2). The mass ratio of graphene oxide to intermediate product is 4.0:1. After shaking, heat it in hydrazine hydrate at 80°C for 5 hours to obtain poly 3,4. -Ethylene dioxythiophene/polystyrene sulfonate-hydrotalcite/graphene PEDOT:PSS-LDH/rGO.

The PEDOT:PSS-LDH/rGO prepared above was examined by scanning electron microscope to characterize the morphology of the material. The specific test method is as follows: Dissolve about 1 mg of PEDOT:PSS-LDH/rGO powder in deionized water, transfer it to a silicon wafer after being evenly dispersed, and observe with SEM high magnification mode. The test results are shown in Figures 1 and 2. From Figures 1 and 2, we can see that the surface structure of the material is complete, showing a two-dimensional lamellar structure as a whole, and the graphene is modified with a regular hexagon with PEDOT:PSS intercalation. LDH nanosheets, which shows that LDH and rGO have a π-π interaction.

The PEDOT:PSS-LDH/rGO prepared above can be used as the filler of PVB resin coating solution, and the preparation method is as follows:

Dissolve PVB with methanol, add the above-prepared PEDOT:PSS-LDH/rGO, the mass ratio of PVB to PEDOT:PSS-LDH/rGO is 20:1, stir evenly to obtain PEDOT:PSS-LDH/rGO-PVB Resin coating solution.

The steel block is pretreated. The pretreatment method is: ultrasonically clean the steel block with deionized water and acetone for 10 minutes to remove impurities and oil on the surface, and then soak it with 0.5% sodium hydroxide solution to remove the surface The oxide layer is obtained, and the steel block sample after pretreatment is obtained.

Place the pretreated steel block sample in the PEDOT:PSS-LDH/rGO-PVB resin coating solution, leave it at room temperature for 24 hours, take it out, clean it with ethanol, and dry it naturally to obtain a surface covered with PEDOT:PSS-LDH/rGO -PVB organic coated steel block samples.

Electrochemical impedance measurement was carried out on the steel block sample covered with PEDOT:PSS-LDH/rGO-PVB organic coating. The measurement method is: the electrolyte is a NaCl solution with a mass concentration of 3.5%, using a three-electrode method, where the reference electrode is a calomel electrode, the counter electrode is a platinum electrode, and the working electrode is the above-obtained surface covered with PEDOT:PSS-LDH/ rGO-PVB organic coated steel block. The test results of electrochemical impedance phase angle and Bode spectrum are shown in Figure 3 and Figure 4:

(1) It can be seen from Figure 3 that the phase angle value of the low frequency region of the steel block sample covered with the organic coating of PEDOT:PSS-LDH/rGO-PVB hardly decreases, and it is maintained at about 90°, indicating the above The obtained surface is covered with PEDOT:PSS-LDH/rGO-PVB organic coating, which can effectively control the diffusion of corrosive media to the surface of the metal substrate.

(2) It can be seen from Fig. 4 that the resistance modulus of the steel block covered with the organic coating of PEDOT:PSS-LDH/rGO-PVB is very large, which is as high as 10 ⁹ Ωcm ^-2 or more, that is, during the corrosion process The resistance of charge transfer is larger, indicating that the above-obtained surface covered with organic coating of PEDOT:PSS-LDH/rGO-PVB can provide the steel block with good anti-corrosion effect and self-repairing ability.

Infrared test was carried out on the corrosion products of the PEDOT:PSS-LDH/rGO-PVB organic coating obtained above to study the protection of the coating on the substrate. For comparison, the above pretreated steel block samples Put them in the pure PVB resin coating solution and rGO-PVB resin coating solution respectively, place them at room temperature for 24 hours and take them out, clean with ethanol and then dry naturally to obtain a pure PVB resin coating on the surface and rGO-PVB resin coating on the surface. Layer of steel block samples. Among them, the preparation method of the PVB resin coating solution is: dissolving PVB with methanol and stirring uniformly to obtain the PVB resin coating solution. The preparation method of the rGO-PVB resin coating solution is as follows: dissolve PVB in methanol, add the above-mentioned rGO to it, the mass ratio of PVB to rGO is 20:1, and stir evenly to obtain the rGO-PVB resin coating solution. The specific test method is: peel off the coating on the surface of the coated steel block soaked in 3.5% NaCl solution, take the corrosion product on the surface of the steel block, and add about 1 mg of the corrosion product powder to the potassium bromide powder In, observe in absorption mode after grinding. The infrared test results are shown in Figure 5. The curve marked "pure coating" in Figure 5 refers to the test result curve representing the surface covered with pure PVB resin coating, and the curve marked "graphene coating" refers to the surface covered with rGO -PVB resin coating test result curve, the curve marked "composite material coating" refers to the test result curve representing the surface covered with PEDOT:PSS-LDH/rGO-PVB resin coating, as can be seen from Figure 5:

The surface is covered with pure PVB resin coating rGO-PVB resin coating, the surface is covered with rGO-PVB resin coating steel sample, and the pre-treated steel sample surface is not covered with coating, the surface obtained above is covered with The corrosion product of the PEDOT:PSS-LDH/rGO-PVB organic coating steel sample shows an extra peak, which reflects the structure of Fe3O4, which indicates that the surface is covered with PEDOT:PSS-LDH/rGO -PVB organic coating can effectively produce a passivation film of iron, which can effectively protect the metal substrate from corrosion. At the same time, the passivation film has a certain repair property for the substrate and avoids the deep corrosion of the metal substrate.

Example 2:

(1) Weigh 0.595 g of magnesium nitrate and 0.96 g of aluminum nitrate into 200 ml of deionized water, mix well, and then add 0.48 g of urea to obtain a raw material solution.

(2) Add 0.06 g of PEDOT:PSS to the raw material solution of step (1), place it in a hydrothermal reaction kettle, shake and heat at 110°C for 24 hours to obtain the intermediate product PEDOT:PSS-LDH.

The PEDOT:PSS-LDH/rGO prepared above was examined by scanning electron microscope to characterize the morphology of the material. The specific test method is the same as that in Example 1. The test results are similar to those shown in Figure 1. The surface structure of the material is complete, and the overall appearance is a two-dimensional lamellar structure. Graphene is modified with PEDOT:PSS intercalated regular hexagons The shape of LDH nanosheets indicates that LDH and rGO have a π-π interaction.

Electrochemical impedance measurement was carried out on the steel block sample covered with PEDOT:PSS-LDH/rGO-PVB organic coating. The measurement method is the same as that in Example 1. The test results show that the same as in Example 1. The surface obtained above is covered with PEDOT:PSS-LDH/rGO-PVB organic coating. The impedance modulus is large. The electrical resistance of charge transfer is large, indicating that the PEDOT:PSS-LDH/rGO-PVB organic coating on the surface obtained above can provide the steel block with a good anti-corrosion effect and self-repairing ability.

Example 3:

(1) Weigh 0.595 g of magnesium nitrate and 0.96 g of aluminum nitrate into 200 ml of deionized water, mix well and add 0.72 g of urea to obtain a raw material solution.

The PEDOT:PSS-LDH/rGO prepared above was examined by scanning electron microscope to characterize the morphology of the material. The specific test method is the same as that in Example 1. The test results are similar to those shown in Figure 1. The surface structure of the material is complete, showing a two-dimensional lamellar structure as a whole, and the graphene is modified with PEDOT:PSS intercalated regular hexagons The shape of LDH nanosheets indicates that LDH and rGO have a π-π interaction.

Example 4:

(1) Weigh 0.595g of magnesium nitrate and 0.96g of aluminum nitrate and dissolve into 200m1 of deionized water

After mixing uniformly, 0.6 g of urea is added to obtain a raw material solution.

(3) Add graphene oxide to the intermediate product prepared in step (2). The mass ratio of graphene oxide to intermediate product is 3.0:1. After shaking, it is heated in hydrazine hydrate at 80°C for 5 hours to obtain poly-3, 4-ethylenedioxythiophene/polystyrene sulfonate-hydrotalcite/graphene PEDOT:PSS-LDH/rGO.

This example is basically the same as Example 1, except that: in step (1), weigh 0.595 g of magnesium nitrate and 0.96 g of aluminum nitrate into 200 ml of deionized water, mix well and add 0.6 g of urea to obtain the raw material Solution.

Example 5:

(3) Add graphene oxide to the intermediate product prepared in step (2). The mass ratio of graphene oxide to intermediate product is 5.0:1. After shaking, heat it in hydrazine hydrate at 80°C for 5 hours to obtain poly 3,4 -Ethylene dioxythiophene/polystyrene sulfonate-hydrotalcite/graphene PEDOT:PSS-LDH/rGO.

Place the pretreated steel block sample in the PEDOT:PSS-LDH/rGO-PVB resin coating solution, leave it at room temperature for 24 hours, then take it out, clean it with ethanol, and dry it naturally to obtain a surface covered with PEDOT:PSS-LDH/rGO -PVB organic coated steel block samples.

Example 6:

Dissolve PVB with methanol, add the above-prepared PEDOT:PSS-LDH/rGO, the mass ratio of PVB to PEDOT:PSS-LDH/rGO is 30:1, stir evenly to obtain PEDOT:PSS-LDH/rGO-PVB Resin coating solution.

The above-mentioned embodiments describe the technical solutions of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Anything done within the principle scope of the present invention Any modification, supplement or substitution in a similar manner shall be included in the protection scope of the present invention.

Claims

A method for preparing graphene composite material is characterized in that it comprises the following steps:

(1) The raw material for the synthesis of hydrotalcite is mixed with poly 3,4-ethylenedioxythiophene/polystyrene sulfonate PEDOT:PSS, and the intermediate product PEDOT:PSS-LDH is prepared by the hydrothermal synthesis method, wherein PEDOT:PSS is inserted Between layer and LDH;

(2) The intermediate product PEDOT:PSS-LDH and graphene oxide are electrostatically self-assembled and the graphene oxide is reduced to obtain the graphene composite material PEDOT:PSS-LDH/rGO.
The method for preparing graphene composite material according to claim 1, wherein the raw materials of the synthetic hydrotalcite include aluminum salt, magnesium salt and urea.
The method for preparing a graphene composite material according to claim 1, wherein the aluminum salt includes one or two of nitrate and sulfate.
The method for preparing a graphene composite material according to claim 1, wherein the magnesium salt includes one or two of nitrate and sulfate.
The method for preparing a graphene composite material according to claim 1, wherein the reaction temperature in the step (1) is 50-80°C.
The method for preparing graphene composite material according to claim 1, characterized in that: in the step (1), the reaction temperature is 60°C.
The method for preparing graphene composite material according to claim 1, characterized in that: in the step (1), the mass ratio of PEDOT:PSS to LDH is (0.69-1.15):1.
8. The preparation method of graphene composite material according to claim 7, characterized in that: in the step (1), the mass ratio of PEDOT:PSS to LDH is 1:1.
The method for preparing a graphene composite material according to claim 1, wherein in the step (1), the molar ratio of aluminum salt, magnesium salt and urea is 1.6:1:(0.8-1.2).
9. The method for preparing a graphene composite material according to claim 9, characterized in that in the step (1), the molar ratio of aluminum salt, magnesium salt and urea is 1.6:1:1.
The method for preparing a graphene composite material according to claim 1, wherein the step (1) is as follows:

Magnesium nitrate, aluminum nitrate, urea and PEDOT:PSS are mixed and put into a reaction tank for hydrothermal synthesis reaction. The reaction product is fully washed with ethanol and/or deionized water and dried to obtain the intermediate product PEDOT:PSS-LDH.
The method for preparing a graphene composite material according to claim 1, wherein in the step (2), the graphene oxide is reduced to graphene in a reducing solution or a reducing atmosphere.
The method for preparing graphene composite material according to claim 1, characterized in that: in the step (2), the reduction reaction temperature is 50-100°C.
The method for preparing a graphene composite material according to claim 13, characterized in that: in the step (2), the reduction reaction temperature is 80°C.
The method for preparing graphene composite material according to claim 1, characterized in that: in the step (2), the mass ratio of graphene oxide to the intermediate product is (3.0-5.0):1.
The method for preparing a graphene composite material according to claim 15, characterized in that: in the step (2), the mass ratio of graphene oxide to the intermediate product is 4.0:1.
A polymer coating comprising a polymer and a graphene composite material prepared by the preparation method of any one of claims 1-16.
The polymer coating of claim 17, wherein the polymer comprises polyvinyl butyral PVB.
The polymer coating according to claim 17, wherein the mass ratio of the polymer to the graphene composite material in the polymer coating is 1:(10-30).
The polymer coating of claim 19, wherein the mass ratio of the polymer to the graphene composite material in the polymer coating is 1:20.
The polymer coating according to claim 17, wherein the preparation method of the polymer coating is: coating, dipping or depositing the polymer coating solution on the surface of the substrate, and curing after drying; The polymer coating solution includes a polymer and the graphene composite material.